ath9k: move coex param updation within mci work

Update all coex parameters in sigle place. So that we can avoid
redoing the same operation in mutiple places and it eases debugging.

Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>